An internal combustion engine is a mature technology, and typically comprises combustion components such as a cylinder, a piston, and a valve, a connecting rod and crankshaft mechanism, a gas distribution and fuel supply system, a ventilation and exhaust gas treatment system, etc. The working principle of the internal combustion engine is well known in the art.
Internal combustion engines can generally be divided into ignition gasoline engines and compression ignition diesel engines.
Only one combustion control mode, i.e., either ignition or compression ignition, is typically employed in one power stroke of the internal combustion engine.
A conventional gasoline engine uses a homogeneous oil and gas ignition and combustion control mode, which is subjected to the defect of slow flame spreading in a time period from ignition of the spark plug to complete combustion of the oil and gas, thereby easily leading to knocks. As a result, it is difficult to achieve a high compression ratio and lean burning, which results in low thermal power conversion efficiency.
A conventional diesel engine adopts an inhomogeneous ignition and combustion control (diffusion compression ignition) mode, which is subjected to the drawback of existence of relatively much soot in the exhaust gases of combustion, thereby causing a waste of fuel. Under heavy load conditions, the problem of emissions of soot and other particulate impurities is especially prominent. In addition, the engine is heavy and operates rather roughly.
Over the past 10 years, homogeneous charge compression ignition gasoline engines have been studied, wherein a multi-point ignition mode is used, and the combustion velocity and the temperature in the combustion chamber are meanwhile controlled, to avoid knocks. Although the engine acquires an increased compression ratio, and lean burning can be realized, such an internal combustion engine can only operate under a relatively fixed, small range of load. Substantial variation in load or rotating speed will cause significant reduction in the thermal power conversion efficiency, or cause knocks. As a result, such engines have rather a narrow utilization range, and have not been used in large scales until now. Moreover, this kind of engine has relatively low power per liter.
Up till now, there is not an internal engine, which uses one single fuel, and can adopt both the diffusion compression ignition control mode and the homogeneous charge compression ignition control mode within one power cycle of the cylinder.